目的：最常用的到达小脑-桥脑角的神经外科方法是乙状结肠后路。本文介绍了乙状结肠的方法，该方法需要对迷宫阻滞的专业知识以及颞骨CT的定量分析。
方法：对接受乙状窦入路前庭神经切除术的患者进行了基于CT的定量测量。18名患者入选，并采取了五项措施：特劳特曼地区，石油悬崖的角度，硬膜硬膜长度及其角度。这些测量值与住院天数之间的关系，操作时间,并探讨了并发症。
结果：后半纤管（PSC）-乙状窦（SS）距离，乙状硬膜-内耳道(IAC)-PSC角,和手术时间是并发症的预测因素。具体来说,PSC-乙状窦距离<11mm,硬脑膜前-IAC-PSC角度<14与并发症风险最高相关.
结论：术前颞骨CT扫描可以引导外科医生通过手术入路的最窄区域。Trautmann的三角形面积和岩壁角度缩小是具有挑战性的，可以面对结合显微内窥镜技术，和光学角度旋转。后迷路入路可以保留听力和最小的小脑回缩。
OBJECTIVE: The most used neurosurgical approach to reach cerebellar-pontine angle is the retrosigmoid route. This article describes the presigmoid approach which requires excellent knowledge of the labyrinthine block together with quantitative analysis of temporal bone CT.
METHODS: CT-based quantitative measurements were obtained in patients undergoing vestibular neurectomy with a presigmoid approach. Eighteen patients were enrolled, and five measures were taken: Trautmann\'s area, the petro-clival angle, presigmoid dura length and its angle. The relationship between these measurements and hospitalization days, operating times, and complications was explored.
RESULTS: The posterior semicircilar canal (PSC)-sigmoid sinus (SS) distance, presigmoid dura- internal auditory canal (IAC)-PSC angle, and duration of surgery are predictors of complications. Specifically, a PSC-sigmoid sinus distance <11 mm, a dura presig-IAC-PSC angle <14 are associated with the highest risk of complications.
CONCLUSIONS: Preoperative temporal bone CT scan can guide the surgeon through the narrowest areas of the surgical approach. Trautmann\'s triangle area and petro-clival angle reduction are challenging and can be faced with combined microscopic-endoscopic technique, and with optics angulation-rotation. The retrolabyrinthine approach can enable hearing preservation and minimal cerebellar retraction.
